No injuries have been reported.
The Bureau of Safety and Environmental Enforcement says inspectors flying over the site Tuesday saw a light sheen covering an area about a half-mile by 50 feet. However, it was dissipating quickly.
The bureau says the leak happened Tuesday morning about 55 miles offshore.
Earlier this month, a gas well leaked for several days before being sealed off the Louisiana coast.
In 2010, an oil rig exploded off the state's coast, leading to a blowout that spewed millions of gallons of oil into the Gulf in the worst offshore disaster in the U.S.